The present invention relates to a method for reacting water soluble (organic solvent insoluble) amino compounds with isocyanates which are highly reactive with water. Examples of such reactions include the preparation of hydantoins and/or hydantoic acid by reacting amino acids or peptides with reactive isocyanates.
The problem with such reactions is that the isocyanate is hydrolyzed by water to form an undesired urea compound. This undesirable reaction competes with the desired reaction between the isocyanate and the amino compound.
The primary technique used by artisans to obviate this problem is to add the isocyanate very slowly to an aqueous solution of the alkali salt of the amino acid with stirring. The reaction is typically conducted at about 50.degree. C. over a two hour period.
U.S. Pat. No. 3,020,145 teaches adding the amino solution slowly to a solution of isocyanate in a water soluble inert solvent, as for example acetone. U.S. Pat. Nos. 4,230,716, 4,093,444 and 3,798,233 have similar disclosures. All of these procedures are relatively slow.